Operating methods of electromechanical pixels are known from spatial light modulators (SLM) for projection displays. Prior art SLMs for projection displays comprise an array of micro-mirrors constructed on a semiconductor backplane. In prior art SLMs, each electromechanical pixel comprises a micro-mirror that is mounted on a pair of hinges above a semiconductor substrate, and a pair of address electrodes with associated drive electronics constructed on the semiconductor substrate.
In operation the SLM is scanned and address voltages are supplied to the address electrodes by the drive electronics. To modulate light, micro-mirrors are selectively reset to first or second deflected positions based on address voltages.
Large area flat panel displays based on electromechanical pixels have been proposed by present inventors and others. The prior art operating methods of SLMs require electromechanical pixels with complex mechanical structures and tight mechanical tolerances. Current manufacturing technology for large area flat panel displays that use glass substrates cannot meet these requirements.
Also, prior art operating methods extensively use mechanical force of micro-mirror hinges which changes with operating time and temperature.
The use of mechanical force, especially for selective positioning of micro-mirrors, causes problems such as resetting micro-mirrors to a wrong position. It also requires selection of operating voltages during the display production, and construction of very uniform hinges.
Flat panel displays usually have larger electromechanical pixels than SLMs for projection displays and need greater electrostatic actuation voltages to operate. In order to display motion images and meet the required addressing speeds, the flat panel displays need greater ratio between the actuation voltages and the address voltages than the prior art operating methods can provide.